Vaccines & Immunotherapy Flashcards
What would make an ideal vaccine?
safe, protective, gives sustained protection, induce neutralizing antibodies, induce protective T cells, low cost, and biologically stable
Types of vaccines
subunit
inactivated whole organism
Live
Recombinant
Types of subunit vaccines
- Single protein: toxoid or expression of recombinant DNA in bacteria or yeast
- Capsular polysaccharide: creates a T-cell independent response – purified polysaccharide and conjugated with non-specific protein to make the response T-cell dependent
- mRNA
- DNA
What is a recombinant virus vaccine?
benign virus expresses antigen of interest
What are protein component vaccines?
- purified subunit from pathogen or from an engineered organism
- induces antibody response
- toxoid
- viral glycoprotein induces antibodies that bind viral surface to block entry into cells
What is a toxoid?
- inactivated bacterial exotoxin
- lost toxicity but retain antigenicity
Describe polysaccharide vaccines
- need to opsonize via anti-polysaccharide antibodies in order to gain immunity
- conjugated to toxoid
- BCR will engulf polysaccharide and present protein antigens on MHC II
Disadvantages of T cell independent antigens
- no isotype switching (can’t change from IgM to IgG for opsonization)
- no affinity maturation
- no memory cells
- insufficient opsonization (only C3b is contributing)
- children under 2 can’t mount these responses effectively
Describe RNA vaccines
- produced by in vitro transcription of DNA template
- need to package RNA-dependent RNA-polymerase
- get into cells with cationic nanoproteins (liposomes) or transfection to hide the RNA
- rapid mass production
- involvement of cellular immunity
Describe DNA vaccines
- more stable than RNA
- risk of integrating into host chromosome
Describe inactivated vaccines
-quick and safe
-elicit antibody responses
-don’t infect cells; no MCH I presentation
(influenza, polio, etc)
Describe pros and cons of live vaccines
- retain immunogenicity
- can infect cells and replicate intracellularly (induce CTL and antibody responses)
- may cause opportunistic infections in immunodeficient patients
What are the 2 types of live vaccines?
1) non-virulent viruses in humans but cross protect related human virus
- ex) using cow pox to defend against small pox
2) attenuated microbes that cannot cause disease in healthy patients
- culture in lab or genetically engineer
- ex) polio, measles, mumps, rubella, etc
What is the viral vector of recombinant viral vaccines?
engineered virus
Example of a recombinant vaccine
Ebola vaccine (rVSV-ZEBOV)
- live VSV is vector
- glycoprotein is replaced with Ebola’s glycoprotein
- cellular and humoral immunity attained